In findings published in the Dec. 2013 issue of the Journal of Archaeological Science, a team of researchers write that the dried-up Winnemucca Lake in western Nevada contains boulders with the oldest petroglyphs ever recorded in North America -- dating back to between 10,500 and 14,800 years ago.

"Some look like multiple connected sets of diamonds, and some look like trees, or veins in a leaf," said study researcher Larry Benson of the University of Colorado. "There are few petroglyphs in the American Southwest that are as deeply carved as these, and few that have the same sense of size."

Added August 14, 2013 at 9:31 a.m.

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New CU-Boulder led research effort dates oldest petroglyphs known in North America | University of Colorado Boulder

Winnemucca Lake was full of water in the past and at times would overflow, covering the carved boulders. The flood waters left behind a carbonate coating, which the scientists used to measure the age of the carvings.

Prior to our study, archaeologists had suggested these petroglyphs were extremely old… Whether they turn out to be as old as 14,800 years ago or as recent as 10,500 years ago, they are still the oldest petroglyphs that have been dated in North America.
– Larry Benson, University of Colorado-Boulder researcher and study co-author

The carbonate layers suggested the boulder was covered twice — between 14,800 and 13,200 years ago and then again between 11,300 and 10,500 years ago. Before the Nevada finding, the oldest North American cave art was thought to be about 6,700 years old, in Oregon.

Added August 14, 2013 at 10:01 a.m.

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New CU-Boulder led research effort dates oldest petroglyphs known in North America | University of Colorado Boulder